[A case-crossover study on air pollutants and the mortality of stroke]

To investigate the short-term effect of particulate matter in air on the mortality of stroke.

Using time-stratified case-crossover study design, an association was examined between stroke mortality and particulate matter with aerodynamic diameter of < 10 microm (PM10) of 2002 - 2004 in Hangzhou city. Meanwhile, the acute health effect of other gaseous pollutants (sulfur dioxide, SO2 and nitrogen dioxide, NO2) was also analyzed.

A total of 9906 deaths of stroke were included. The crude stroke mortality was 83.54 per 100 000. After being adjusted for meteorological factors, when an increase of 10 microg/m3 in PM10, SO2 and NO2 in three days was noticed, it appeared that the increases of mortality of stroke were 0.56% (95% CI: 0.14%-0.99%), 1.62% (95% CI: 0.26% - 3.01%) and 2.07% (95% CI: 0.54% - 3.62%) respectively. There was no distinct association in multi-pollutant models. In sensitivity analysis, the associations were found in all single-pollutant models but not statistically significant in multi-pollutant models after replacing the missing values.

It is suggested that the short-term elevation in PM10 as well as SO2 and NO2 daily concentrations were related to the increase of stroke mortality in Hangzhou city.